Belief revision, epistemic conditionals and the Ramsey test

Abstract

Epistemic conditionals have often been thought to satisfy the Ramsey test (RT): “If A, then B” is acceptable in a belief state G if and only if B should be accepted upon revising G with A. But as Peter Gardenfors has shown, RT conflicts with the intuitively plausible condition of Preservation on belief revision. We investigate what happens if (a) RT is retained while Preservation is weakened, or (b) vice versa. We also generalize Gardenfors' approach by treating belief revision as a relation rather than as a function.